WO2003083157A1

WO2003083157A1 - NITRIDED Mo ALLOY WORKED MATERIAL HAVING HIGH CORROSION RESISTANCE, HIGH STRENGTH AND HIGH TOUGHNESS AND METHOD FOR PRODUCTION THEREOF

Info

Publication number: WO2003083157A1
Application number: PCT/JP2003/003912
Authority: WO
Inventors: Jun Takada; Masahiro Nagae; Makoto Nakanishi; Tomohiro Takida
Original assignee: Japan Science And Technology Agency; National University Corporation Okayama University; A.L.M.T.Corp.
Priority date: 2002-03-29
Filing date: 2003-03-27
Publication date: 2003-10-09
Also published as: ATE533870T1; EP1491651A4; KR20040105796A; CA2480787A1; EP1491651A1; JP4302930B2; EP1491651B1; KR100611725B1; JP2003293116A; US20060054247A1

Abstract

A nitrided Mo alloy worked material having high corrosion resistance, high strength and high toughness, characterized in that it comprises a base Mo alloy worked material and, dispersed in the inside thereof, fine nitride particles having been formed by the nitriding of a metal element capable of forming a nitride present in the inside of the Mo alloy worked material and, formed on the surface thereof, a Mo nitride layer having been formed by the nitriding of a worked structure or a recovered structure on the surface; and a method for producing the nitrided Mo alloy worked material which comprises subjecting an alloy worked material containing Mo as a base phase and at least one of Ti, Zr, Hf, V, Nb and Ta as a solute of a solid solution to an internal nitriding with gradually elevating temperatures, and then subjecting the resultant product to an external nitriding. The nitrided Mo alloy worked material is novel and exhibits satisfactorily high corrosion resistance and a high strength under an ultra-severe conditions, such as in a boiled conc. sulfuric acid solution (for example, an aqueous 75 % H2SO4 solution at 180°C), and further, has a high strength at an elevated temperature and also a high toughness at a low temperature, which properties have never seen in the conventional materials.

Description

明細書高耐食性■高強度 ·高靭性窒化処理 M o合金加工材とその製造方法技術分野 Description High corrosion resistance ■ High strength ・ High toughness Nitriding Mo alloy processed material and manufacturing method

本発明は、内部窒化処理と外部窒化処理を組み合わせて強度 ·靭性の他に耐食性を改善した窒化処理 M o合金加工材とその製造方法に関する。背景技術 The present invention relates to a nitrided Mo alloy processed material having improved corrosion resistance in addition to strength and toughness by combining internal nitriding and external nitriding, and a method for producing the same. Background art

M oは融点が約 2 6 0 0 °Cと高く、他の高融点金属に比べて比較的に機械的強度に優れており、熱膨張率が小さく、電気伝導性■熱伝導性が良好、溶融アル力リ金属や塩酸に対する耐食性が良好、などの特徴を有し、電極、管球用部品、半導体部品、耐熱構造部品、原子炉用材料などの用途がある。 Mo has a high melting point of about 260 ° C., has relatively high mechanical strength compared to other high melting point metals, has a low coefficient of thermal expansion, and has good electrical conductivity and good thermal conductivity. It has characteristics such as good corrosion resistance to metal and hydrochloric acid, and has applications such as electrodes, tube parts, semiconductor parts, heat-resistant structural parts, and materials for nuclear reactors.

しカゝし、加工組織を有する加工材ではクラック伝播が困難なので高靭性を示すのに対して、ー且、加熱（約 1 0 5 0 °C以上）後の再結晶材では、クラック伝播が容易になり脆化するので高温強度が十分ではなく、高温強度を改善した M o合金として T Z M合金（Mo-0. 5ΤΪ-0. 08Zr- 0. 03C)や T Z C (Mo - 1. 5Nb-0. 5Ti_0. 03Zr - 0. 03C) 合金が開発されている。 On the other hand, cracked propagation is difficult in a processed material having a processed structure, and crack propagation is difficult. On the other hand, in a recrystallized material after heating (approximately 150 ° C or more), crack propagation is difficult. High temperature strength is not sufficient because it becomes easy and becomes brittle, and TZM alloy (Mo-0.5ΤΪ-0. 08Zr- 0.03C) and TZC (Mo-1.5Nb- 0.5 Ti_0. 03Zr-0.03C) alloys are being developed.

本発明者らは、先に、多段階の内部窒化処理を行って超微細窒化物を分散含有させた M oなどの高融点金属合金加工材において、加工材の少なくとも表面側は加工組織を維持したままとすることにより高靭性 ·高強度が得られることを見出した（特許文献 1、非特許文献 1〜 3 ) 。 M oは上記のように優れた特性を有するが、熱濃硫酸や硝酸などの酸化性の酸に対する耐食性がない。耐食性改善に関して、本発明者らは、 Moおよび Mo系合金を窒化処理して厚さ 0. 5〜 10 μ inの Mo 2 N層を設けた高耐食性 Mo系複合材料を開発した（特許文献 2) 。 The present inventors have previously conducted a multi-stage internal nitridation process to maintain a processed structure on at least the surface side of a processed material of a refractory metal alloy processed material such as Mo in which ultrafine nitride is dispersed and contained. It has been found that high toughness and high strength can be obtained by keeping this state (Patent Document 1, Non-Patent Documents 1-3). Mo has excellent properties as described above, but does not have corrosion resistance to oxidizing acids such as hot concentrated sulfuric acid and nitric acid. Regarding the improvement of the corrosion resistance, the present inventors have developed a high corrosion-resistant Mo-based composite material in which a Mo and a Mo-based alloy are subjected to nitriding treatment to provide a Mo 2 N layer having a thickness of 0.5 to 10 μin (Patent Document 2). ).

特許文献 1 特開 2001— 73060号公報 Patent Document 1 JP 2001-73060 A

特許文献 2 特開平 1 1— 286770号公報 Patent Document 2 JP-A-11-286770

非特許文献 1 長江正寛、高田潤、竹元嘉利、平岡裕、吉尾哲夫、日本金属学会誌、 64 (2000) 747〜 750 Non-Patent Document 1 Masahiro Nagae, Jun Takada, Yoshitoshi Takemoto, Yutaka Hiraoka, Tetsuo Yoshio, Journal of the Japan Institute of Metals, 64 (2000) 747-750

非特許文献 2 長江正寛、高田潤、竹元嘉利、平岡裕、吉尾哲夫、日本金属学会誌、 64 (2000) 751〜 754 Non-Patent Document 2 Masahiro Nagae, Jun Takada, Yoshitoshi Takemoto, Yutaka Hiraoka, Tetsuo Yoshio, Journal of the Japan Institute of Metals, 64 (2000) 751-754

非特許文献 3 高田潤、長江正寛、竹元嘉利、平岡裕、まてりあ、 40 (2001) 、 666-667 発明の開示 Non-Patent Document 3 Jun Takada, Masahiro Nagae, Yoshitoshi Takemoto, Yutaka Hiraoka, Materia, 40 (2001), 666-667

超苛酷腐食条件下（例えば、沸騰濃硫酸溶液）での装置材料としては、現在まで T a金属しか有用でなかった。し力し、 T a金属は低強度であり、特に高温度での強度は低く、高強度が要求される装置 '構造材料としては適していない。また、 T a金属に代わる材料として本発明者らが開発した上記の高耐食性 Mo系複合材料は製造過程において母材が再結晶する結果、材料全体が脆化する欠点があつた。 To date, only Ta metal has been useful as equipment material under ultra-severe corrosion conditions (eg, boiling concentrated sulfuric acid solution). However, Ta metal has low strength, especially at high temperatures, and is not suitable as a structural material for equipment that requires high strength. In addition, the above high corrosion-resistant Mo-based composite material developed by the present inventors as a material replacing the Ta metal had a disadvantage that the entire material was embrittled as a result of recrystallization of the base material during the manufacturing process.

そこで、本発明は、沸騰濃硫酸溶液（例： 75%H₂S0₄水溶液（180°C) ) など超苛酷腐食条件下でも十分に高耐食性および高強度を示し、その上、高温においても高強度で、かつ低温でも高靭性を有する、これまでの材料にはない物性を合わせ持つ革新的材料とその効率的な製造方法の提供を目的とする。 Therefore, the present invention provides sufficiently high corrosion resistance and strength even under ultra-severe corrosion conditions such as a boiling concentrated sulfuric acid solution (eg, 75% H ₂ SO ₄ aqueous solution (180 ° C)), and furthermore, it can be used at high temperatures. The aim is to provide innovative materials with high strength even at low temperatures and high toughness even at low temperatures, combining physical properties not found in conventional materials, and efficient production methods for them.

本発明者らは、 Mo加工材に内部窒化処理と外部窒化処理を組み合わせることにより、効率的に安価に高強度■高靭性とともに酸化性の酸に対しても優れた耐食性を有する M o合金加工材が得られることを見出した。 By combining internal and external nitriding treatments on Mo-processed materials, the present inventors have found that Mo alloys have high strength, high toughness and excellent corrosion resistance to oxidizing acids at low cost. It has been found that a processed material can be obtained.

すなわち、本発明は、 Mo合金加工材中に固溶した窒化物形成金属元素が内部窒化されて生成した微細窒化物が内部に分散され、さらに、加工材表面の加工組織または回復組織が外部窒化されて生成した M o窒化物層が表面に形成されていることを特徴とする高耐食性 ·高強度 ·高靭性窒化処理 Mo合金加工材である。また、本発明は、加工材表面の Mo窒化物は δ—Μο Ν、 γ— M02Nまたは /3— Μο₂Νの少なくとも 1種からなることを特徴とする上記の窒化処理 Mo合金加工材である。 That is, according to the present invention, the fine nitride generated by internally nitriding the nitride-forming metal element dissolved in the Mo alloy processing material is dispersed therein, and further, the processed tissue or the recovery structure on the surface of the processed material is externally formed. This is a highly corrosion-resistant, high-strength, high-toughness nitrided Mo alloy processed material characterized by having a Mo nitride layer formed on the surface formed by nitriding. Further, the present invention provides the above-mentioned nitriding-treated Mo alloy processing material, wherein the Mo nitride on the surface of the processing material is at least one of δ-ΜοΜ, γ-M02N or / 3-3ο2 _2. is there.

また、本発明は、 Mo窒化物層と加工材内部の母相との間の層が加工組織または回復組織を持つことを特徴とする上記の窒化処理 M o合金加工材である。また、本発明は、合金の内部が再結晶組織であることを特徴とする上記の窒化処理 M o合金 ¾ェ材である。 Further, the present invention is the above-mentioned nitrided Mo alloy processed material, wherein the layer between the Mo nitride layer and the parent phase inside the processed material has a processed structure or a recovered structure. Further, the present invention is the above-mentioned nitrided Mo alloy base material, wherein the inside of the alloy has a recrystallized structure.

さらに、本発明は、 Moを母相とし、 T i、 Z r、 H f、 V、 Nb、 T aの少なくとも 1種を固溶した合金加工材に段階的に処理温度を上げて内部窒化処理を行い、次いで外部窒化処理を行うことを特徴とする請求の範囲第 1項ないし第 4 項のいずれかに記載の窒化処理 Mo合金加工材の製造方法である。 Further, in the present invention, the processing temperature is increased stepwise to an alloy processing material in which at least one of Ti, Zr, Hf, V, Nb, and Ta is used as a solid phase with Mo as a mother phase. 5. The method for producing a nitrided Mo alloy processed material according to claim 1, wherein a nitriding treatment is performed, and then an external nitriding treatment is performed.

また、内部窒化処理を N₂ガスで行い、次いで外部窒化処理を NH₃ガスで行うことを特徴とする上記の窒化処理 M o合金加工材の製造方法である。図面の簡単な説明 Further, there is provided the above-mentioned method for producing a nitrided Mo alloy processed material, wherein the internal nitriding is performed with N ₂ gas, and then the external nitriding is performed with NH ₃ gas. BRIEF DESCRIPTION OF THE FIGURES

第 1図は、本発明の窒化処理 Mo合金加工材の断面構造を示す模式図である。第 2図は、本発明の窒化処理 M o合金加工材を製造する工程における内部窒化処理（1) 〜（3) の各段階の加工材の組織を示す模式図である。第 3図は、実施例 1および実施例 2により得られた窒化処理 M o合金加工材と比較例（純 M o材料）の腐食試験結果を示すグラフである。第 4図は、実施例 2により得られた窒化処理 Mo合金加工材の図面代用断面組織写真 (a) および曲げ試験後の窒化処理 Mo合金加工材試片の図面代用マクロ写真 (b) である。発明を実施するための最良の形態 FIG. 1 is a schematic view showing a cross-sectional structure of a nitrided Mo alloy processed material of the present invention. FIG. 2 is a schematic diagram showing the structure of the processed material at each stage of the internal nitriding processes (1) to (3) in the process of producing the nitrided Mo alloy processed material of the present invention. FIG. 3 is a graph showing the corrosion test results of the nitrided Mo alloy processed material obtained in Example 1 and Example 2 and the comparative example (pure Mo material). Fig. 4 is a photograph of a cross-sectional structure of a nitrified Mo alloy processed material obtained in Example 2 as a substitute for a drawing (a) and a macro photograph of a nitrified Mo alloy processed material specimen after a bending test (b). It is. BEST MODE FOR CARRYING OUT THE INVENTION

第 1図は、本発明の窒化処理 M o合金加工材の断面構造の一例を示す模式図である。第 1図に示す本発明の窒化処理 Mo合金加工材は、加工材 1の内部の表面側に分散したナノサイズ窒化物粒子 2の層、加工材の表面の加工組織または回復組織層 3が外部窒化されて生成した Mo ₂ N表面層 4と加工材の内部の Mo再結晶層 5からなる三層構造となる。加工材が比較的薄い場合には内部まで完全に加ェ組織が保持されたままとすることも可能であり、その場合は M o再結晶層 5のない二層構造となる。 FIG. 1 is a schematic diagram showing an example of a cross-sectional structure of a nitrided Mo alloy processed material of the present invention. FIG. 1 shows a nitrided Mo alloy processed material according to the present invention. It has a three-layer structure including the Mo ₂ N surface layer 4 formed by nitriding and the Mo recrystallized layer 5 inside the processed material. If the work material is relatively thin, it is possible to keep the texture completely inside, in which case a two-layer structure without the Mo recrystallized layer 5 is obtained.

加工材は、 M oを母相とし、 T i、 Z r、 Hf 、 V、 Nb、 T aの少なくとも 1種を固溶した希薄合金を圧延などの加工を行ったものである。なお、希薄合金とは固溶体合金の溶質元素の濃度が約 5重量％以下の微少量含有される合金をいラ。本発明の高耐食性 ·高強度 ·高靭性窒化処理 M o合金加工材は下記の内部窒化処理（1 ) 〜（3 ) と外部窒化処理（4 ) により製造される。第 2図の（1 ) 〜The work material is a material obtained by subjecting a dilute alloy in which at least one of Ti, Zr, Hf, V, Nb, and Ta is dissolved to a solid phase with Mo as a mother phase, such as rolling. Note that a dilute alloy is an alloy that contains a small amount of solute elements in solid solution alloys of about 5% by weight or less. The high corrosion resistance, high strength, and high toughness nitriding treatment of the present invention is manufactured by the following internal nitriding treatments (1) to (3) and external nitriding treatment (4). Fig. 2 (1) ~

( 3 ) は、段階的に処理温度を上げて行う内部窒化処理（1 ) 〜（3 ) の各段階の加工材の組織を示す模式図である。 (3) is a schematic diagram showing the structure of the processed material at each stage of the internal nitriding treatments (1) to (3) performed by gradually increasing the treatment temperature.

( 1 ) 第 1段窒化処理：窒化雰囲気中において再結晶上限温度以下で、かつ再結晶下限温度一 2 0 0 °C以上の温度で加熱して、窒化物形成用金属元素の超微細窒化物粒子を分散形成させる。第 1段窒化処理では、希薄合金加工材の加工組織 X 1を維持したまま窒素を加工材に拡散することにより母相中に固溶されている窒化物形成金属元素を優先窒化して直径 1〜 2 n m程度のサブナノ板状窒化物粒子を形成し、母相に分散させる。なお、優先窒化とは、母相の金属ではなく窒化物形成元素のみが優先的に窒化される現象をいう。この窒化処理により生成した析出粒子のピン止め効果により加工材表面部の再結晶温度が上昇する。 . (1) First-stage nitriding treatment: Heating in a nitriding atmosphere at a temperature lower than the upper limit of recrystallization and at a temperature higher than the lower limit of recrystallization of 200 ° C. The oxide particles are dispersed and formed. In the first-stage nitriding treatment, nitrogen is diffused into the work material while maintaining the work structure X1 of the dilute alloy work material, thereby preferentially nitriding the nitride-forming metal element that is dissolved in the parent phase to obtain a diameter 1 Sub-nano-plate-like nitride particles of about 2 nm are formed and dispersed in the matrix. Note that preferential nitriding refers to a phenomenon in which only a nitride-forming element, not a metal in a parent phase, is preferentially nitrided. The recrystallization temperature of the surface of the work material increases due to the pinning effect of the precipitated particles generated by this nitriding treatment. .

( 2 ) 第 2段窒化処理：窒化雰囲気中において第 1段窒化処理で得られた加工材の再結晶下限温度以上の温度で加熱して、超微細窒化物粒子を粒成長させ安定化させる。第 2段窒化処理により析出粒子の成長 ·安定化により再結晶温度がさらに上昇する。窒化時に加工材内部は再結晶し加工組織 X 2が残るが、加工材が比較的薄い場合（3 mm以下）には内部まで完全に加工組織の保持が可能である。 (2) Second-stage nitriding: The workpiece obtained by the first-stage nitriding is heated in a nitriding atmosphere at a temperature equal to or higher than the recrystallization lower limit temperature to grow and stabilize ultrafine nitride particles. The recrystallization temperature further increases due to the growth and stabilization of precipitated particles by the second-stage nitriding treatment. During nitriding, the inside of the work material is recrystallized and the work structure X2 remains, but when the work material is relatively thin (3 mm or less), the work structure can be completely retained inside.

( 3 ) 第 3段以降の窒化処理：窒化雰囲気中において前段処理で得られた加工材の再結晶下限温度以上の温度で加熱して、窒化物粒子を粒成長させ安定化させる。第 3段以降の窒化処理は、加工組織 X 3を残したまま、窒化物粒子の更なる成長 (3) Third and subsequent nitriding treatments: The nitrided particles are heated in a nitriding atmosphere at a temperature equal to or higher than the recrystallization lower limit temperature of the work material obtained in the preceding treatment to grow and stabilize the nitride particles. In the third and subsequent nitriding treatments, further growth of nitride particles while leaving the processed structure X3

-安定化を目的とするものであり、太さ約 1 0 n m、長さ約 5 0 n mの棒状窒化物粒子が M o母相に均一に分散する。第 3段以降の第 4段、第 5段などの窒化処理は適宜行うことができる。 -For stabilization, rod-shaped nitride particles of about 10 nm in thickness and about 50 nm in length are uniformly dispersed in the Mo matrix. The third and subsequent stages, such as the fourth and fifth stages The processing can be appropriately performed.

(4) 外部窒化処理：強い窒化処理により Moの窒化物層を表面に形成する。窒化雰囲気は、アンモエアガス雰囲気、 N₂ガス雰囲気、フォーミングガス雰囲気 (水素ガス：窒素ガス =1 ： 9〜5 ： 5) 、およびこれら三者のガスのそれぞれにプラズマ放電させた雰囲気などいずれでもよい。形成される Mo窒化物は δ— ΜοΝ、 γ— Mo 2Νまたは ]3— Mo ₂Νの少なくとも 1種からなる。 Mo窒化物表面層と加工材内部の母相との間には加工組織または回復組織が残るようにする。 (4) External nitridation: A strong nitride treatment forms a Mo nitride layer on the surface. The nitriding atmosphere may be any of an ammonia gas atmosphere, a N ₂ gas atmosphere, a forming gas atmosphere (hydrogen gas: nitrogen gas = 1: 9 to 5: 5), and an atmosphere in which each of these three gases is subjected to plasma discharge. . The formed Mo nitride comprises at least one of δ-δοΜ, γ-Mo ₂ Mo or] 3—Mo ₂ Ν. A processed or recovered structure is left between the Mo nitride surface layer and the parent phase inside the processed material.

外部窒化処理の加熱処理温度と皮膜の厚さの関係を Mo— 0. 5wt%T i合金の場合について下記の表 1に示す。加熱温度が高いほど膜厚が大きくなる。耐食性の観点からは膜厚は厚い方がよいといえるが、厚くするにつれ翻性（曲げ特性）が低下することが分かった。したがって、靭性と耐食性を兼ね備える条件としては、 900°C以下の外部窒化処理（厚さ約 3mm以下）とする必要がある。 (表 1) Table 1 below shows the relationship between the heat treatment temperature of the external nitriding treatment and the film thickness for the case of Mo-0.5wt% Ti alloy. The higher the heating temperature, the larger the film thickness. From the viewpoint of corrosion resistance, it can be said that the thicker the film, the better. However, it was found that as the thickness increases, the transversibility (bending property) decreases. Therefore, as a condition that combines toughness and corrosion resistance, it is necessary to use an external nitriding treatment (thickness of about 3 mm or less) at 900 ° C or less. (table 1)

本発明の窒化処理 Mo合金加工材は、半導体 'セラミックス '金属高温焼成用支持板、高 ΜΑΠ熱炉用ヒーター、高温加熱炉用部材、腐贪環境下で使用される化学設備 ·装置用構造材（高温焼却炉等も含む）、超臨界 ·亜臨界溶液反応装置材料などの他、硫酸、硝酸などの酸化性の酸用の耐酸容器や管材、超苛酷腐食条件下（例えば、沸縢濃硫酸溶液）での装置材料、超高温ヒーター、金属射出成型金型、ディ一ゼルェンジン用噴射ノズルなどとして有用である。

The nitrided Mo alloy processed material of the present invention is a semiconductor 'ceramics' metal high-temperature firing support plate, a high-temperature heating furnace heater, a high-temperature heating furnace member, and a chemical equipment and equipment structure used in a corrosive environment. Materials (including high-temperature incinerators, etc.), supercritical and subcritical solution reactor materials, acid-resistant containers and tubes for oxidizing acids such as sulfuric acid and nitric acid, and extreme severe corrosion conditions It is useful as an equipment material below (for example, boiling sulfuric acid concentrated sulfuric acid solution), an ultra-high temperature heater, a metal injection mold, and a spray nozzle for diesel engines.

(実施例） (Example)

実施例 1 Example 1

厚さ 1 mm、一辺 1 Ommの平板状の Mo— 1. 0 w t % T i合金加工材を N Plated Mo 1 mm thick, 1 Omm side, Mo—1.0 wt% Ti

₂ガス（1気圧）気流中にて加熱温度を変えて 4段内部窒化した。加熱温度は、Four-stage internal nitriding was performed in a _two- gas (1 atm) air flow while changing the heating temperature. The heating temperature is

900 °C→ 950 °C→ 1200 °C→ 1500 °Cとした。 900 ° C → 950 ° C → 1200 ° C → 1500 ° C.

この多段窒化処理により、加工材の表面域（表面から深さ約 200 μπΐまで）は加工 ·回復組織を保持し（内部は再結晶組織）、加えて微細な T i N粒子を分散析出させた。さらに、 NH₃ガス（1気圧）気流中にて 1000°C、 4時間外部窒化処理して加工材の表面に厚み 14. Ομπιの Mo窒化物（y -Mo₂Nなど）層を形成した。 By this multi-stage nitriding treatment, the surface area of the processed material (from the surface to a depth of about 200 μπΐ) retains the processed and recovered structure (the recrystallized structure inside), and also diffuses and precipitates fine TIN particles. Was. In addition, an external nitride treatment is performed at 1000 ° C for 4 hours in a stream of NH ₃ gas (1 atm) to form a 14.Ομπι thick Mo nitride (y-Mo ₂ N, etc.) layer on the surface of the processed material. did.

この加工材では、加工材の表面が Mo窒化物層、その内側が微細 T i N粒子が分散析出した加工 ·回復結晶粒組織の Moを母相とする固溶元素の窒化物層、さらにその内側は大きな等軸再結晶粒組織の Mo合金層の三層構造を呈する。 In this processed material, the surface of the processed material is a Mo nitride layer, and the inner side is a nitride layer of a solid solution element having Mo as a mother phase in a processed / recovered grain structure in which fine TiN particles are dispersed and precipitated. In addition, the inside has a three-layer structure of a Mo alloy layer with a large equiaxed recrystallized grain structure.

次に、苛酷腐食環境下での耐食性を検討するため、 75%濃硫酸沸騰溶液 (1 85°C) 中で腐食試験を行った結果を第 3図に示す。第 3図中には、比較試料として純 Moの結果も示す。純 Moの腐食速度は 8 mm/年と高く、激しく腐食するのに対して、本発明の加工材は 0. 076mmZ年（実施例 1 ) と殆ど腐食せず、ほぼ完全耐贪性（腐食速度：く 0. 05mmZ年）を示すことが見出された。実施例 2 Next, Fig. 3 shows the results of a corrosion test conducted in a 75% concentrated sulfuric acid boiling solution (185 ° C) in order to examine the corrosion resistance in a severely corrosive environment. Fig. 3 also shows the result of pure Mo as a comparative sample. The corrosion rate of pure Mo is as high as 8 mm / year, and corrodes violently, whereas the processed material of the present invention hardly corrodes at 0.076 mmZ (Example 1) and has almost perfect corrosion resistance (corrosion resistance). (Speed: 0.05 mmZ). Example 2

Mo - 0. 5w t%T i合金加工材を N2ガス（1気圧）気流中にて加熱温度を変えて 3段内部窒化した。温度は、 900°C→1200°C→1500°Cとした。 3段内部窒化処理した Mo合金を、さらに、 1気圧 NH₃気流中で 900°C、 4 h加熱（外部窒化処理）して、加工材表面に Mo窒化物（δ— ΜοΝ， γ -Mo 2N) 層を均一に形成した。この多段窒化処理により、微細 T i N粒子が分散析出し、加工 '回復結晶粒組織の內部窒化層は 310/zmであり、 Mo窒化物の外部窒化層は 2· 8 mであった。また、加工衬表面の X線回折パターンより、 δ — Mo Νと —Mo ₂ Nの外部窒化物層の形成が認められた。 Heating temperature of Mo-0.5wt% Ti alloy material in N2 gas (1 atm) Was changed to three-stage internal nitriding. The temperature was 900 ° C → 1200 ° C → 1500 ° C. The three-stage internally nitrided Mo alloy is further heated (external nitridation) at 900 ° C for 4 hours in a 1 atm NH ₃ gas stream, and Mo nitride (δ-ΜοΝ, γ-Mo 2N ) The layer was formed uniformly. By this multi-stage nitriding treatment, fine TiN particles were dispersed and precipitated, the upper nitrided layer of the processed and recovered grain structure was 310 / zm, and the outer nitrided layer of Mo nitride was 2.8 m. Further, from the X-ray diffraction pattern of the working衬表surface, [delta] - Mo New and -Mo ₂ N forming the outer nitride layer was observed.

75%濃硫酸沸騰溶液（185°C) 中で腐食試験を行った結果を第 3図に示す。実施例 2の加工材では、 0. 046 mm/年と殆ど腐食せず、完全耐食性（腐食速度：く 0. 05 mm,年）を示す。 Figure 3 shows the results of a corrosion test performed in a 75% concentrated sulfuric acid boiling solution (185 ° C). The processed material of Example 2 hardly corrodes at 0.46 mm / year and shows complete corrosion resistance (corrosion rate: 0.05 mm / year).

さらに、実施例 2の 3段内部窒化処理（900 °C→ 1200 °C→ 1500 °C) した加工材とその後に外部窒化処理（900°C— 4h) した加工材の室温における曲げ強度（降伏強度と最大強度）を表 2に示す。また、第 4図に（a) 断面組織写真と（b) 曲げ試験後の試片のマクロ写真を示す。 Furthermore, the bending strength at room temperature of the three-stage internal nitriding (900 ° C → 1200 ° C → 1500 ° C) and the external nitriding (900 ° C-4 h) of Example 2 (Yield strength and maximum strength) are shown in Table 2. Fig. 4 shows (a) a photograph of the cross-sectional structure and (b) a macro photograph of the specimen after the bending test.

(表 2) (Table 2)

表 2より、実施例 2の 900 °C、 4 h外部窒化処理した加工材（M o窒化物層厚さ：約 2. 8 / m) の降伏強度と最大強度は、いずれも 3段内部窒化処理材 (高強度 ·高靱性化）と同程度の高い応力値を示すことが見出された。即ち、本発明の窒化処理 M o合金力卩ェ材は高耐食性とともに極めて高い強度を有することが明らかとなつた。産業上の利用可能性

From Table 2, the yield strength and the maximum strength of the work material (Mo nitride layer thickness: about 2.8 / m) that was externally nitrided at 900 ° C for 4 h in Example 2 were all three-step internal nitrided. It was found that it showed a high stress value comparable to that of the treated material (high strength and high toughness). That is, it has been clarified that the nitriding-treated Mo alloy material of the present invention has extremely high strength as well as high corrosion resistance. Industrial applicability

本発明は、窒化処理のみにより効率的に安価に高強度■高靭性とともに酸化性の酸に対しても優れた耐食性を有し、極限腐食環境に対応できる窒化処理 M o合金加工材を提供するもので、従来の M oまたは M o合金の各種用途はもちろん、超苛酷腐食条件下（例えば、沸騰濃硫酸溶液）での装置材料、超高温ヒーター、金属射出成型金型、ディーゼルエンジン用嘖射ノズルなどの各種用途への M o材料の実用化に貢献するものである。 The present invention provides a nitriding treated Mo alloy material that has high strength, high toughness, excellent corrosion resistance against oxidizing acids, and can be used in extremely corrosive environments, efficiently and inexpensively only by nitriding. In addition to the various uses of conventional Mo or Mo alloys, equipment materials under ultra-severe corrosive conditions (eg, boiling concentrated sulfuric acid solution), ultra-high temperature heaters, metal injection molds, diesel engine molds This contributes to the practical use of Mo materials for various applications such as injection nozzles.

Claims

請求の範囲 The scope of the claims

1. Mo合金加工材中に固溶した窒化物形成金属元素が内部窒化されて生成した微細窒化物が内部に分散され、さらに、加工材表面の加工組織または回復組織が外部窒化されて生成した M o窒化物層が表面に形成されていることを特徴とする高耐食性 ·高強度■高靭性窒化処理 Mo合金加工材。 1. The fine nitride generated by internal nitridation of the nitride forming metal element dissolved in the Mo alloy processing material is dispersed inside, and the processed or recovered structure on the surface of the processed material is externally nitrided. High corrosion resistance · High strength ■ High toughness nitriding treatment Mo alloy processed material characterized by having a Mo nitride layer formed on the surface.

2. 加工材表面の Mo窒化物は δ—Mo N、ー Mo ₂Nまたは ]3— Mo 2 Nの少なくとも 1種からなることを特徴とする請求の範囲第 1項記載の窒化処理 M o 合金加工材。 2. Mo nitride workpiece surface δ-Mo N, over Mo ₂ N or] 3- Mo 2 nitriding treatment as set forth in claim 1, wherein claims, characterized in that it consists of at least one N M o alloy Processing materials.

3. Mo窒化物層と加工材内部の母相との間の層が加工組織または回復組織を持つことを特徴とする請求の範囲第 1項または第 2項記載の窒化処理 M o合金加工材。 3. The nitriding Mo alloy processing according to claim 1 or 2, wherein the layer between the Mo nitride layer and the parent phase inside the processing material has a processing structure or a recovery structure. Wood.

4. 合金の内部が再結晶組織であることを特徴とする請求の範囲第 1項ないし第 3項のいずれかに記載の窒化処理 M o合金加工材。 4. The nitrided Mo alloy processed material according to any one of claims 1 to 3, wherein the inside of the alloy has a recrystallized structure.

5. Moを母相とし、 T i、 Z r、 Hf 、 V、 Nb、 T aの少なくとも 1種を固溶した合金加工材に段階的に処理温度を上げて内部窒化処理を行い、次いで外部窒化処理を行うことを特徴とする請求の範囲第 1項ないし第 4項のいずれかに記載の窒化処理 M o合金加工材の製造方法。 5. Mo is used as a parent phase, and an internal nitriding treatment is performed by gradually increasing the processing temperature to an alloy processing material in which at least one of Ti, Zr, Hf, V, Nb, and Ta is dissolved, and then externally. 5. The method for producing a nitrided Mo alloy processed material according to claim 1, wherein the nitriding treatment is performed.

6. 内部窒化処理を N ₂ガスで行い、次いで外部窒化処理を NH 3ガスで行うことを特徴とする請求の範囲第 5項記載の窒化処理 Mo合金加工材の製造方法。第 1図 6. The method for producing a nitrided Mo alloy processed material according to claim 5, wherein the internal nitriding is performed with N ₂ gas, and then the external nitriding is performed with NH 3 gas. Fig. 1

3 Three

ナノサイズ窒化物粒子

Nano-sized nitride particles

第 2図 Fig. 2

纖 O6 ,さAV

Fiber O6 AV

娘 Daughter

( /rain)纖翻 (/ rain) Fiber translation

■ ■